Thermal conductivity enhancement of reduced graphene oxide via chemical defect healing for efficient heat dissipation

Abstract

As next-generation miniaturized electronics are being developed with higher power density, a need for effectively dissipating the generated heat during the device operation is becoming ever greater. Nano carbons such as graphene are strong candidates for heat dissipating materials with lightweights owing to their low densities with extraordinary thermal properties rooted from their highly crystalline and conjugated structures. Starting from a relatively less ordered, cheaper, and mass producible graphene oxide (GO), to this end, we herein describe a sequential chemical transformation to obtain a higher ordered crystalline and conjugated structure of the GO. A conventional reduction followed by a chemical defect healing process via intramolecular cross-dehydrogenative coupling gradually increased graphitic and crystalline structures of the GO as evidenced by a variety of spectroscopic and microscopic experiments. Consequently, the thermal conductivity of the final product was enhanced to 9.90 W/mK, corresponding to over 500% of the starting GO (1.92 W/mK). Moreover, the defect healed GO itself was successfully used as a heat dissipating material, quickly lowering its temperature by -36 degrees C during a continuous heating at 100 degrees C. Finally, we also demonstrated the defect healed GO as filler to enhance the thermal conductivity of the polymeric composites. (C) 2018 Elsevier Ltd. All rights reserved.